Telephone system



May 20,l 1941.

I J. A. KATER TELEPHONE SYSTEM 2 Sheets-Sheet 1 Filed March 5, 1939 www Arrow/VE@f May zo, 1941. J. A. ATER 2,242,391'

TELEPHONE SYSTEM Filed March 3, 1939 2 sheets-sheet 2 ATTORNEY Patented May 20, 1941 TELEPHONE SYSTEM Joseph A. Kater, Teaneck, N. J., assigner to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application March 3, 1939, Serial No. 259,499

10 Claims. (Cl. 179-18) This invention relates to telephone systems and particularly to systems employing automatic switches of the step-by-step type.

An object of the invention is to provide circuit arrangements for step-by-step switches which are more reliable in operation and simpler in regard to the circuit-making equipments required.

Heretofore circuit arrangements have been used for two-motion step-by-step switches in which contact springs are actuated by the movement of the so-called double dog at the beginning of the movement of the shaft and released at the end of the movement of the shaft to provide a holding circuit for the stepping magnets to insure that the magnets take a full step in switching arrangements where the stepping circuits for the magnets are controlled directly by dial pulses incoming overa line.

It is a feature of the present invention to provide circuit arrangements that include the use of contacts on the double dog and a stepping magnet having self-interrupting contacts to insure that a switch takes a full step each time it is operated by this magnet during the huntingstepping movements of the switch.

In selector switching circuits heretofore used, a special relay is employed during the step-bystep hunting movement to control the roto-r magnet operations when busy lines are encountered. It-is another feature of the present invention to simplify such prior circuit arrangements for hunting by eliminating this special relay and delegating the function thereof to other elements employed in these circuits.

The invention has been illustrated in the accompanying drawings in which:

Fig. 1 sho-Ws in a somewhat diagrammatic form the main features of a standard step-by-step switch of the Strowger type on which contacts have been shown operated by a double dog;

Fig. 2 shows these contacts in more detail; and

Figs. 3 and 4 show automatic telephone systems of two different types with the selector circuit arrangements shown in detail to illustrate the application of the invention to such standard selector circuits.

Referring no-w to Figs. 1 and 2, Fig. 1 shows the usual operating shaft I having two sets of contact brushes 2, 3 and 4 operating on co-rrespending banks of terminals 5, 6 and 1, where terminals 5 are sleeve connections and 6 and' 'I are respectively tip and ring connections. 'Ihis shaft may be elevated by the vertical magnets 8 operating on armature 9 to cause the pawl rIll attached to this armature to engage the vertical ratchet on the shaft. The usual rotary magnets I2 operate on armature I3 to cause pawl I4 attached thereto to engage the rotary ratchet I5 on the shaft to rotate the brushes to a desired set of terminals. The usual double dog I6 is provided to hold the shaft in actuated positions and the release magnet I'I may operate its armature I 8 toiengage the double dog to cause it to disengage the shaft to permit it to return to normal under tension of the usual spring arrangements I9. A set of contacts 20 and 2| are attached to the frame member 22 and the inne-r spring 20 thereof normally engages the double dog I5 through the insulation stud 23. When the double dog is raised to disengage a tooth when the shaft is either elevated or rotated, this spring 20 engages spring 2I. When the double dog returns to rest on the next tooth, the connection between these contacts 20 and 2| is opened. Thus on each step of the switch the contacts 20 and 2| are momentarily closed, the closure taking place at the beginning of a step and the opening taking place at the end of the step. Advantage of this operation of the contacts 20 and 2| is taken in providing a circuit arrangement according to the applicants invention to insure the switch to take full steps during its step--by-step hunting movement.

Fig. 3 shows an automatic telephone system disclosed diagrammatically except the selector circuit in which the applicants application has been applied. A connection. may be established from a subscriber |00 to a subscriber IBI in a well-known manner `as far as the line finder |02 and connector |04 are concerned. If it is assumed that a connection has been established through a line finder |02, the closure of this connection causes relay |06 to operate over a circuit from battery through the upper winding of this relay, contacts of relay |07 over the subscribers loop through the line finder, contacts of relay |01, lower Winding of relay |06 to ground at the eleventh step contacts |00. Relay |06 closes an obvious circuit for the operation of relay |09. The subscriber then dials the first digit and on the first impulse relay |06 releases. 'Il'xis closes a circuit for the operation of a vertical magnet ||0 and relay III from battery through the Winding of this magnet, winding of relay contacts of relays |09, |06 and |01 to ground. Relays III and |09 remain operated during the succeeding impulses. The Vertical magnet I|0 operating in response to these suca rotary direction to take one step. 'The en-' ergizing circuit is then opened at the rotary off-normal contacts H and this energizing circuit is also opened through the right-hand outer armature and back contact of the rotary magnet soon after it begins'to operate. vHowever, it should be noted at this time that the double dog H5 will be raised as it begins to ride over a tooth in the rotary ratchetl I1 and thus closes a connection between the contacts H8 as described in connection with Figs. 1 and 2. The closure of this circuit provides a continued energizing and holding circuit for the rotary magnet H2 from battery through the Winding of this magnet, contacts 8, the inner right-hand armature and front contact of magnet H2 to ground at contacts of relay |09. When the shaft has completed its step, the double dog I I5 will be lowered into the next tooth of the ratchet ||1 and thus open the connection through contacts H8 to release the rotary magnet` H2. As the original energizing circuit for the rotary magnet H2 was opened by the operation of the rotary off-normal contacts H5, the rotary magnet will not take any further steps unless a busy sleeve terminal is encountered. If the connector circuit to which the brushes of the selector have been connected is busy, a ground will be supplied on the sleeve terminal such as 20. This causes the closure of a circuit for the rotary magnet H2 from battery through the winding of this magnet, the outer right-hand self-interrupting contacts,

contacts of relay III, contacts of the release tained operated during this step by the contacts' connector is encountered when no ground willV be supplied on the terminal such as |20. This closes a circuit for the operation of relay |01 from battery, winding and contacts of the' magnet H2, contacts of relay III and magnet ||3, vertical off-normal contacts H4 through the terminal |20 and sleeve brush, upper armature and back contact of relay |01, Winding of relay |01, rotary off-normal contacts H5, the eleventh step contacts |08 to ground at relay |09. This causes the operation voi relay |01 which extends the tip and ring conductors over the upper and lower outer armatures and front contacts of this relay through to the idle connector which then operates in the usual manner to make this switch busy and apply a ground on the sleeve conductor. Relay |01 is thereby locked in operated condition from battery through the rotary magnet Winding and its self-interrupting contacts,

contacts of relay HI, contacts of release magnetl H3, vertical off-normal contacts H4, winding of relay |01, rotary off-normal contacts H5, eleventh step contacts |08, inner upper armature and front contact of relay |01, the sleeve brush and sleeve terminal |20 to ground. 'Ihe resistance of the winding of relay |01 prevents the rotary magnet H2 from operating in this circuit. The operation of relay |01 also releases relay |06 which in turn releases relay |09. The circuits are now in condition for transmission of the next digit which operates the connector |04 to extend the connection to the subscriber I 0I, which is then rung and when he answers the call talking between the two subscribers |00 and |0| may begin. When the connection is released the` ground at the terminal |20 is removed and relay |01 releases which now causes the operation of release magnet H3 from battery throughy the winding of this magnet, vertical oir-normal contacts H4, contact of relays |09, |06 and |01 to ground.

The circuit shown inFig. 4 is similar to that shown in Fig. 3 except that the selector is of a somewhat diierent type. In this case when a calling subscriber |25 has established a connection through the line nder |26, relay |21 operates over a circuit similar to that described in connection with the operation of relay |06. Relay |21 closes an obvious circuit for the operation of relay |28 and the first digit may now be dialed. This causes the operation of the vertical magnet |29 and relay |30 from battery through the winding of this magnet, contacts of relays |28 and |21, winding of relay |30 to ground at relay |28. After the vertical magnet has operated the required number of steps,` the relay |30 'releases and closes a circuit for the rotary magnet |32 from battery through the winding ofl this magnet and its outer right-hand selfinterrupting contacts, contacts of relay |30, vertical off-normal contacts I 34, eleventh stepcontacts |35, contacts of relays |21 and |36 to ground. As the rotary magnet |32 operates, it opens its energizing circuit'through its outer right-hand armature and back contact. On the rotation of the shaft the double dog |31 is raised to close a connection between the contacts |38 and these contacts close a holding circuit for the rotary magnet |32 from battery through the Winding of this magnet, contacts |38, inner right-hand armature and front contact of the rotary magnet |32, winding of relay |30, contacts of relay |28 to ground. Relay |30 operates in this circuit and opens the original energizing circuit for the rotary magnet that extended through the outer right-hand armature and back contact of magnet |32 and the armature and back contact of relay |30. When the shaft has completed the step the double dog |31 returns to normal position in the next tooth on the rotary ratchet and opens the contacts |38 and thus causes the release of the rotary magnet |32. This insures the taking of a complete step by the shaft. Relay |30 is slow in releasing and remains operated for a short period after the step has been taken to determine whether or not the connector circuit on which the brushes of this selector havelanded is busy. If it is busy a ground will be supplied on the sleeve terminal |40 and :thus cause the rotary magnet |32 to be again energized over a circuit from battery through the Winding of this magnet, the outer right-hand self-interrupting'contacts, contacts of relays |30 vand |36 overthe upper sleeve brush to ground at the terminal |40. The rotary magnet in operating opens this circuit and the locking 'circuit through contacts |38 is again closed to maintain the magnet operated until the step is completed. If then an idle connector circuit is encountered, there will be no ground on terminal |40 which permits relay |36 to operate from battery, winding of magnet |32 and its outer right-hand amature and back contacts, contacts of relays |30 and |36, the upper and lower sleeve brushes through terminal |40, make-before break contacts of relay |36 through the winding of this relay to ground at contacts of relay |28. Relay |36 opens the circuit for the rotary magnet |32 to prevent it from taking another step and locks over a circuit from battery through the Vertical magnet |20, upper inner armature and front contact of relay |36, winding of this relay to ground supplied immediately at contacts of relay |28 and later through the usual busy ground placed on the terminal |40 from the connector through the upper middle armature and front contact of relay |33. The resistance of this relay is suiiicient to prevent the vertical magnet from operating at this time. The operation of relay |36 causes the release of relays |21 and |28 and the circuits are now ready for the transmission of the remaining impulses to cause the connector |45 to extend the connection to the called subscriber |41 which is then rung and when he answers the connection is completed for talking. When the sub-scribers hang up, the ground on terminal |40 is removed causing the release of relay |36 which then closesy the circuit for the release magnet |50 from battery through the winding of this magnet, vertical off-normal contacts |34, contacts of relays |28, |21 and |36 to ground causing the release ofthe switch.

What is claimed is:

1. The combination in a step-by-step switch having a brush shaft, a stepping magnet responsive to each of a series of energizations for imparting to said shaft a movement corresponding to one step, a circuit for energizing said magnet to initiate the step movement of the shaft, contact means controlled b-y .the magnet for opening said circuit intermediate the beginning and end of the step movement, a second circuit for the magnet, and means operated by the movement of said shaft for closing said second circuit prior toI the opening of said first circuit and for holding said second circuit closed until the shaft reaches the end of the step movement.

2. In combination in a step-by-step switch having a brush shaft, a stepping magnet responsive to each of a series of energizations for imparting to said shaft a movement corresponding to one step, a circuit for energizing said magnet to initiate the step movement of the shaft, contact means controlled by the magnet fo-r opening said circuit intermediate the beginning and end of each step movement, a second circuit for said step movement, a circuit extending through said contacts for energizing said magnet to initiate its operation, a' second set of contacts controlled by said shaft tocloseshortly after said shaft begins to take a step movement and to open when it completes said step movement, and a circuit extending through said second set of contacts for energizing said magnet to complete its operation.

4. In a step-by-step switch, a shaft, a stepping mechanism for advancing said shaft in steps, a magnet for actuating said mechanism to advance said shaft one step for each energization of said magnet, a circuit for energizing the magnet to begin the stepping action of the shaft for its first step, a -circuit for energizing the magnet to begin the stepping action of the shaft for succeeding steps, means for permanently disabling said first circuit after the first step movement and for closing said second circuit, a set of contacts, a mechanism controlled during the stepping actions of said shaft for closing said set of con-y tacts as soon as a stepping action has begun and for opening said contacts as s oon as a stepping action is completed, and a circuit controlled by said contacts for maintaining lthe energization of .said magnet as long as said contacts `are closed to insure the shaft taking a full step each time a stepping action has begun.

5. In a step-by-step switch, a shaft, a stepping mechanism for advancing said shaft in steps, a magnet for actuating said mechanism to advance said shaft one step for each energization' of said magnet, a circuit for energizing the magnet to initiate the step movement of the shaft, means controlled by said magnet for opening sai-d circuit soon after each step movement has begun,

, a set of contacts, a mechanism controlled during each step movement of said shaft for closing said set of contacts as soon as a step movement begins `and for opening said contacts as soon as a step movement is completed, and a circuit for maintaining said magnet energized as long as said contacts are closed to insure the shaft taking a full step each time a step movement has begun.

6. In a step-by-step switch, a magnet for advancing the switch step by step, a circuit for energizing thefmagnet to begin the stepping action of the switch for each step, contacts controlled by said magnet to open said circuit, contacts controlled by said switch to close as soon as a stepping action has begun and to open when a stepping action is completed, and a second circuit controlled by said latter contacts for maintaining the energization of said magnet as longA as said latter contacts are closed to insure the switch taking the complete steps.

'7. In a telephone system, a step-by-step switch comprising sets of terminals arranged in a bank, a set of brushes movable by said switch to engage the terminals in said bank in succession, lines connected to said sets of terminals, `a magnet, a first circuit for beginning the energization of said magnet for the taking of a first step to cause the brushes to connect to the first set of terminals and its associated line, means for disabling said circuit shortly after the switch begins to take said first step, a second circuit for beginning the energization of said magnet for the taking of additional steps operative if succeeding sets of terminals are busy, a third circuit operative if a set of terminals to which the brushes have been advanced are idle for disabling said second circuit and a fourth circuit controlled by the movement of the switch for maintaining the magnet' energized until lthe' switchhas completed each step.

8. tIn a telephone system, a step-by-step switch, a magnet, means responsive Ito each operation of said magnet for moving said switch one step, a first circuit for energizing said magnet, means for closing said circuit once, means for opening said rst circuit shortly after the magnet starts to operate, a second energizing circuit for said magnet, means for repeatedly closing said second circuit each time the switch has taken a step and the magnet is released and for opening said second circuit shortly after the magnet starts to operate, a third energizing circuit'for said magnei-l and means for closing said third circuit each time shortly after the switch starts to move and opening said third circuit when the switch has been moved a step to insure -the complete'operation of the magnet to make the switch take complete steps.

9. In combination, in a stepeby-step switch,

having a brush shaft, a stepping magnet for imparting to said 'shaft a movement corresponding to one step for each complete operation of said magnet, a first circuit for energizing said magnet for taking a first step only, ofi-normal contacts for opening said circuit in response to the taking of the rst step by said switch, a second circuit for energizing'said magnet for the taking of succeeding steps, a pair of contacts controlled by the energization of the magnet to Open said two circuits shortly after the energization of the magnetbegins, a Asecond pair of contacts controlled by :the Venergization of said magnet, a third pair of contacts controlled by said switch to close as soon as the stepping action has begun and to open when a stepping action is completed and a third circuit controlled by said second and third pair of contacts for maintaining the energization of the magnet as long as said last-mentioned pair of contacts are closed.

10. In a step-by-step switch, a shaft a stepping mechansm for advancing said shaft in steps, a magnet 'for'actuating said mechanism to' advance the shaft one step for each energization'of said magnet, a circuit for energizing the magnet'to begin the stepping action of the shaft for its first step, a circuit for energizing the magnet to begin the stepping action of the shaft for succeeding steps, means for Vpermanently disabling said rst circuit after the first step movement and for closing said second circuit, means controlledrby said magnet for opening said second circuit soon after the second and veach succeeding step movement has begun, a set of contacts, a mechannism controlled during the stepping action of said `shaft for closing said set of contacts as soon as the steppingv action has begun and forv opening said contacts as soon as the stepping action is completed, and a circuit controlled by said contacts for maintaining the energization yof said magnet as long as said contacts are closed to insure the shaft taking a full step/each time a stepping action has begun.

JOSEPH A. KATER. 

